The organic light-emitting device having an organic electroluminescent element (hereinafter may also be referred to as an organic EL element) as a light-emitting source comprises a supporting substrate, one or two or more organic EL element(s) formed on the supporting substrate, and a sealing member laminated to the supporting substrate through the organic EL element so that the organic EL element is sealed therebetween. In the above configuration, one or two or more organic EL element(s) on the supporting substrate is sealed with the supporting substrate and the sealing member to be protected from the external environment.
The organic EL element formed on the supporting substrate may be either one or two or more monochromatic organic EL element(s) or numbers of organic EL elements emitting light of each color of RGB (red, green, and blue). An organic light-emitting device having the former configuration is mainly used for a light source and an organic light-emitting device having the latter configuration is mainly used for a color display device.
The organic EL element constituting the above organic light-emitting device has a basic configuration in which a light-emitting layer of an organic light-emitting material is formed as a thin film between an anode and a cathode. In the organic EL element having such a basic configuration, when a voltage is applied between both electrodes, holes are injected from the anode and electrons are injected from the cathode. Then, the holes and the electrons are coupled with each other in the light-emitting layer to generate light emission.
It is usually difficult for the organic EL element to obtain desired characteristics with the basic configuration alone. Therefore, in addition to the light-emitting layer, a predetermined organic layer is provided. Examples of the predetermined organic layer may include a hole injection layer, a hole transport layer, an electron injection layer, and an electron transport layer.
The electron injection layer is formed conventionally by vapor-depositing an electron injecting material such as Ba, BaO, NaF and LiF in high vacuum. These electron injecting materials are unstable in air. When the formed electron injection layer is left under the air environment, the electron injection layer is easily reacted with moisture or oxygen to be chemically changed. This degradation of the electron injection layer causes a dark spot or lowering of the life in the organic light-emitting device.
In the manufacturing of the organic light-emitting device having the electron injection layer, in order to prevent the above degradation of the electron injection layer, the lamination of the sealing member is performed in a vacuum atmosphere (for example, see Patent Document 1, Patent Document 2, and Patent Document 3).
However, when the lamination of the sealing member is performed in a vacuum atmosphere, the whole system including a device for laminating the sealing member is required to be retained in vacuum, so that the device becomes enlarged and the step becomes complicated, which leads to a cause for cost-up of the organic light-emitting device.